1. Field of the Invention
The present invention relates generally to fluid valving in a base assembly of a hydraulic damper. In particular, an assembly and method are disclosed which permit the selected compression and preloading of a spring in the compression valve assembly so that the valve opens in response to a predetermined fluid pressure in the damper.
2. Statement of the Related Art
Twin tube hydraulic shock absorbers and struts have compression valve assemblies with a well-known valve cage. The valve cage includes an annular skirt and a fluid passage. A relief valve is inserted inside of the skirt and blocks the flow of fluid through an orifice. A helical valve spring extends upwardly from a spring retainer to contact the relief valve so that it is operative to control fluid flow through the orifice. The spring retainer is received in a groove on the inner surface of the annular skirt.
Conventional assemblies are prepared by measuring the fixed height of the compression valve assembly. In other words, the groove provided in the annular skirt is designed for an optimal spring rate based on the height of the compressed spring. However, during a production run, part tolerances can vary, including the respective heights of the valve cage, relief valve and valve spring. When variances occur, the predetermined location of the groove may not provide the optimal compression of the valve spring. Consequently, the fluid flow through a compression valve assembly can vary, resulting in less than optimal operation of the damper.
The art continues to seek improvements. It is desirable to provide an economical compression valve assembly utilizing a spring to control fluid through a flow passage. Furthermore, it is desirable to preload each spring at substantially the same level in a production run to ensure uniformity of the valve operation.